The contract will provide for the operation of a synthesis laboratory for the preparation by chemical synthesis target lead compounds. The natural products and their derivatives will be evaluated as antitumor and AIDS antiviral agents. The specific objectives are to: .optimize biological activity of natural product leads by designing and preparing by chemical synthesis analogue series which will elucidate the structure activity relationships (SAR) for that lead; .use SAR information to develop simplified more readily synthesized analogues, which may incorporate partial structures; .devise efficient synthesis routes to lead natural products or their analogues, starting from commercially available intermediates or readily purchased natural products and carry out those syntheses to afford amounts of compound required for secondary testing.